The present invention relates to laser devices that produce an output that is substantially a single longitudinal mode. In some applications, it is desired that the output of a laser device be substantially a single longitudinal mode. One benefit of producing a single longitudinal mode output is the reproducibility of the pulse outputs. Reproducibility of pulse outputs is desirable for some measurements or scientific experiments. As discussed below, more than one longitudinal mode in an output will modulate the output. This modulation may be random and unpredictable.
Additionally, the laser device may be used in a system with non-linear crystals. Non-linear crystals are used in frequency doublers, and parametric oscillators or amplifiers. The conversion efficiencies of non-linear crystals may depend upon the pulse-shape of the laser device output. For that reason, it is desired that the laser device output be substantially a single longitudinal mode so that the pulse shape is predictable.
One difficulty maintaining a laser device in a single longitudinal mode is that the cavity length and gain characteristics of the laser device drift with temperature changes.
It is desired to have a laser device that can maintain its output in a single longitudinal mode even when the cavity length and gain characteristics drift with temperature changes.